scholarly journals Measurement and Analysis of Infrasound Signals Generated by Operation of High-Power Wind Turbines

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6544
Author(s):  
Tomasz Malec ◽  
Tomasz Boczar ◽  
Daria Wotzka ◽  
Michał Kozioł
Keyword(s):  
Wind Turbines ◽  
High Power ◽  
Sound Pressure ◽  
Operating Time ◽  
Weather Conditions ◽  
Acoustic Energy ◽  
Working Environment ◽  
Frequency Range ◽  
Noise Levels ◽  
Measurement And Analysis

The development of wind energy and the increasing number of installed wind turbines make it necessary to assess them in terms of the nuisance of the emitted infrasound noise generated by such devices. The article presents the results of measurements and analyses of infrasound emitted during the operation of wind turbines installed in various locations in Poland. Comparative analysis of noise levels in the infrasound and audible range has shown that acoustic energy is mainly in the low and infrasound frequency range, and the measured levels depend significantly on the weighting curves used. On the basis of the results, it was confirmed that the sound pressure level of infrasound signals emitted by the operation of high-power wind turbines, regardless of wind velocity, weather conditions, design solutions of turbines, operating time, rated capacity, does not exceed the criteria specified in the applicable legislation dealing with the assessment of infrasound noise on the working environment.

scholarly journals Prediction of Turbulent Boundary Layer Induced Noise in the Cabin of a BWB Aircraft

2012 ◽  
Vol 19 (4) ◽  
pp. 693-705 ◽  
Author(s):  
Joana Rocha ◽  
Afzal Suleman ◽  
Fernando Lau
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Sound Pressure ◽  
Pressure Level ◽  
Interior Noise ◽  
Analytical Models ◽  
Frequency Range ◽  
Noise Levels ◽  
Cabin Noise ◽  
Cabin Interior

This paper discusses the development of analytical models for the prediction of aircraft cabin noise induced by the external turbulent boundary layer (TBL). While, in previous works, the contribution of an individual panel to the cabin interior noise was considered, here, the simultaneous contribution of multiple flow-excited panels is analyzed. Analytical predictions are presented for the interior sound pressure level (SPL) at different locations inside the cabin of a Blended Wing Body (BWB) aircraft, for the frequency range 0–1000 Hz. The results show that the number of vibrating panels significantly affects the interior noise levels. It is shown that the average SPL, over the cabin volume, increases with the number of vibrating panels. Additionally, the model is able to predict local SPL values, at specific locations in the cabin, which are also affected with by number of vibrating panels, and are different from the average values.

Acoustic characteristics of wall jets over a rough surface

2020 ◽  
Vol 68 (5) ◽  
pp. 316-327
Author(s):  
Rahul S. Arackal ◽  
T.J.S. Jothi
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Smooth Surface ◽  
Sound Pressure ◽  
Acoustic Measurements ◽  
Frequency Range ◽  
Noise Levels ◽  
Wall Jets ◽  
Acoustic Characteristics ◽  
Plate Length

The effects of surface roughness on the noise emissions from wall jets with a plate length (L) of 40 cm are presented in this article. The surface roughness of the plate considered for the study is in the range of 5 to 19 mm, and the jet velocity at the nozzle exit is varied from 20 to 56 m/s. Acoustic measurements of the different roughness plate wall jets are carried out at a distance of 60 cm from the jet axis and compared with that of a smooth surface. The spectral results indicate that the noise emissions from rough surface wall jets are lower in the frequency range (0.3â–“3.0 kHz), and the corresponding sound pressure levels are lower by around 5 dB compared to the noise from a smooth surface. Concurrently, the surface roughness is significant in generating higher noise levels by around 5 dB in the frequency range of 3 to 12 kHz compared to its counterpart.

scholarly journals ENVIROMENTAL ASPECTS OF NOISE ASSESSMENT AND REGULATION IN THE DESIGN OF PORT COMPLEXES IN RUSSIA

Akustika ◽  
2019 ◽  
Vol 34 ◽  
pp. 72-78
Author(s):  
Vladimir Zhigulski ◽  
Daria Zhigulskaya ◽  
Vladimir Shuisky ◽  
Ekaterina Chebynina ◽  
Vitaly Panichev
Keyword(s):  
Sound Pressure ◽  
Animal Species ◽  
Riparian Ecosystems ◽  
Frequency Range ◽  
Noise Levels ◽  
Natural Ecosystems ◽  
Physiological Processes ◽  
Sound Pressure Levels ◽  
Noise Assessment ◽  
Natural Test

A comparative analysis of various biological objects sensitivity to acoustic effects is being conducted. For many animal species, the frequency range at which sounds are heard is very different from that for humans and may not even intersect with it. The total frequency range at which various animals can hear covers at least eight orders of magnitude (from hundredths of Hz to hundreds of kHz), while for humans this interval is limited to only four orders of magnitude. Thus, the existing anthropocentric standards for permissible noise levels are unsuitable for regulating their impacts on natural ecosystems and it is necessary to develop standards for sound pressure levels in the entire specified frequency range that are acceptable for the most sensitive recipients. For terrestrial and riparian ecosystems and protected areas, natural test subjects are birds, for which noise levels of 35-40 dBA do not cause pathological changes in behavior and physiological processes. This level can tentatively be considered as maximum permissible for man-made noise and for the noise of ports in particular. More reliable results will be given by regulating the permissible sound pressure levels in the entire frequency range based on reactions of the most sensitive recipients in each octave.

The influence of external conditions on sound pressure in the pistonphone at the infrasound frequency range

2020 ◽  
pp. 67-72
Author(s):  
A. V. Konkov ◽  
D. V. Golovin
Keyword(s):  
Environmental Conditions ◽  
Sound Pressure ◽  
Primary Method ◽  
Frequency Range ◽  
External Conditions ◽  
Numerical Estimations

The influence of environmental conditions on a sound pressure reproduced by the primary method in the measuring chambers of the Pistonphone in the frequency range from 1 mHz to 250 Hz is estimated. Numerical estimations of influence of environmental conditions on sound pressure in pistonphone measuring chambers are given and special requirements to system of maintenance of required external conditions are specified.

scholarly journals Case Study in a Working Environment Highlighting the Divergence between Sound Level and Workers’ Perception towards Noise

2020 ◽  
Vol 17 (17) ◽  
pp. 6122
Author(s):  
Chun-Yip Hon ◽  
Illia Tchernikov ◽  
Craig Fairclough ◽  
Alberto Behar
Keyword(s):  
Noise Exposure ◽  
Health And Safety ◽  
Sound Level ◽  
Working Environment ◽  
Noise Levels ◽  
Hearing Conservation ◽  
Attitudes And Perceptions ◽  
Noise Measurements ◽  
Survey Responses ◽  
Excessive Noise

Excessive noise levels are a prevalent issue in food processing operations and, although there have been numerous studies on occupational noise, no single study has used a concurrent mixed-methods approach. Employing this study design allows for an understanding of the level of convergence (similarity) between measured noise levels and workers’ attitudes and perceptions towards noise. This, in turn, allows for the identification of potential challenges with respect to the implementation of hearing conservation efforts. In this study, spot noise measurements were collected using a sound level meter. One-on-one interviews were conducted with workers to determine attitudes and perceptions towards noise in their workplaces. Subsequently, the results of the noise measurements (quantitative data) were integrated with the survey responses (qualitative data) to identify convergence. The majority of the noise measurements were found to exceed 85 dBA—the criterion mandated by the local occupational health and safety legislation. Although all study participants felt that it was noisy in the workplace, a large proportion of respondents indicated that the noise was not bothersome. With workers’ perception being contradictory to the measured noise levels, it is a challenge to implement hearing conservation measures unless changes are made to raise the awareness of the risks associated with excessive noise exposure.

scholarly journals Measurement of Underwater Acoustic Energy Radiated by Single Raindrops

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2687
Author(s):  
Shu Liu ◽  
Qi Li ◽  
Dajing Shang ◽  
Rui Tang ◽  
Qingming Zhang
Keyword(s):  
Ambient Noise ◽  
Sound Pressure ◽  
Tap Water ◽  
Acoustic Energy ◽  
Underwater Sound ◽  
Underwater Noise ◽  
Energy Characteristics ◽  
Sound Energy ◽  
Dipole Radiation ◽  
Series Of Experiments

Underwater noise produced by rainfall is an important component of underwater ambient noise. For example, the existence of rainfall noise causes strong disturbances to sonar performance. The underwater noise produced by a single raindrop is the basis of rainfall noise. Therefore, it is necessary to study the associated underwater noise when drops strike the water surface. Previous research focused primarily on the sound pressure and frequency spectrum of underwater noise from single raindrops, but the study on its sound energy is insufficient. The purpose of this paper is to propose a method for predicting the acoustic energy generated by raindrops of any diameter. Here, a formula was derived to calculate the underwater sound energy radiated by single raindrops based on a dipole radiation pattern. A series of experiments were conducted to measure the underwater sound energy in a 15 m × 9 m × 6 m reverberation tank filled with tap water. The analysis of the acoustic energy characteristics and conversion efficiency from kinetic to acoustic energy helped develop the model to predict the average underwater sound energy radiated by single raindrops. Using this model, the total underwater sound energy of all raindrops during a rainfall event can be predicted based on the drop size distribution.

The variability of naturally occurring magnetic field levels: 10 Hz to 8 kHz

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. F187-F197 ◽  
Author(s):  
Ben K. Sternberg
Keyword(s):  
Magnetic Field ◽  
Noise Level ◽  
Monsoon Season ◽  
Signal Frequency ◽  
Time Interval ◽  
Frequency Range ◽  
Noise Levels ◽  
Controlled Source ◽  
Naturally Occurring ◽  
Minimum Noise

The variability of naturally occurring magnetic fields in the frequency range from [Formula: see text] over a period of one year was studied. Contour plots for the [Formula: see text], [Formula: see text], and [Formula: see text] components and for frequencies of 10, 100, 1000, 2000, and 8000 Hz were produced. Average, minimum, maximum, and the standard deviations of these fields were also calculated for 12 distinctive time intervals. In the 1– to 8–kHz frequency range, the noise levels are typically higher at night. In the 10- to 100-Hz frequency range, the noise levels are typically higher during the day. During mid- to late-summer, there is frequent thunderstorm activity, known in the southwest United States as the monsoon season. The magnetic field levels are often very high during this time period. These variability ranges can be used to estimate the lowest levels of noise that may be encountered during field surveys, which iswhat the authors are looking for when running controlled-source electrical method surveys. These variability ranges can also be used to estimate the highest levels that may be encountered, which is what the authors are looking for when running natural-source electrical methods surveys, such as audio frequency magnetotelluric (AMT) surveys. These measurements of magnetic field strength variability show that better data for controlled-source electrical measurements can be obtained using the minimum noise level measurements, as opposed to using signal integration or signal averaging with all of the data. The minimum noise level is found by using frequency bins adjacent to the signal-frequency bin. Likewise, if one is interested in measuring the naturally occurring magnetic field data, using the maximum values during each time interval makes AMT measurements possible when the natural signal level is very low, particularly in the AMT dead zone around [Formula: see text].

Influence of Wind-produced Noise on Orientation in the Sole (Solea solea)

1994 ◽  
Vol 51 (6) ◽  
pp. 1258-1264 ◽  
Author(s):  
J. P. Lagardère ◽  
M. L. Bégout ◽  
J. Y. Lafaye ◽  
J. P. Villotte
Keyword(s):  
Spatial Distribution ◽  
Ambient Noise ◽  
Sound Intensity ◽  
Weather Conditions ◽  
Fish Populations ◽  
Positioning System ◽  
Noise Levels ◽  
Orientation Behaviour ◽  
Solea Solea ◽  
Swimming Trajectories

Sole (Solea solea), telemetered in an enclosure using an acoustic positioning system, changed their swimming trajectories and orientation behaviour as a function of wind strength and direction. Monitoring of the spatial variation in both wind-generated currents and noise spectra in the enclosure indicates that these behavioural changes correspond to patterns in the spatial distribution of noise and to sound intensity. Thus, our observations indicate that sole perceives and reacts to horizontal variability in ambient noise levels. Such behaviour may be important in determining movements of fish populations at sea during poor weather conditions.

Sign in / Sign up

Export Citation Format

Share Document